Abstract

Quantum Cascade Lasers (QCLs) are semiconductor devices that, currently, have been observed to emit radiation from ~ 2.6 µm to 250 µm (1 to 100 terahertz range of frequencies). They have established themselves as the laser of choice for spectroscopic gas sensing in the mid-wavelength infrared (3-8 µm) and long-wavelength infrared (8-15 µm) region. In the 4-12 µm wavelength region, the highest performing QCL devices, in terms of wall-plug efficiency and continuous wave operation, are indium phosphide (InP) based. The ultimate goal is to incorporate this InP-based QCL technology to silicon (Si) substrate since most opto-electronics are Si-based. The main building blocks required for practical QCL-on-Si integrated platforms were demonstrated and will be covered in this presentation. The experimental results of a 40-stage indium phosphide based quantum cascade laser grown on a lattice-mismatched germanium-coated silicon substrate with metamorphic buffer (M-buffer) is discussed. The QCL's strain-balanced active region was composed of Al0.78In0.22As/In0.73Ga0.27As and an 8 µm-thick all-InP waveguide. Since the M-buffer was insulating, the wafer was processed into ridge-waveguide chips with lateral current injection scheme. Lasing was observed from 78K up to 170K for QCL-on-Si devices. Also discussed is the first room temperature operation of QCL grown on a lattice-mismatched gallium arsenide (GaAs) substrate with metamorphic buffer (M-buffer). Similar to QCL-on-Si, a lateral injection scheme was utilized since M-buffer was insulating. Lasing was observed from 78K up to 303 K for QCL-on-GaAs. Material characterization of QCL-on-InP, QCL-on-GaAs, and QCL-on-Si using Transverse Electron Microscopy (TEM) will also be covered in this presentation. A very small section, 10 µm x 10 µm, of the QCL active region was used to give an estimate of the defect density for each of the QCL configuration. Lastly, characterization of the material quality of the remaining 6-inch wafer of QCL-on-Si using photoluminescence spectroscopy (PL) will be discussed. This method helped determined the best portion of the remaining material for subsequent processing into ridge waveguide devices.

Notes

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Graduation Date

2020

Semester

Summer

Advisor

Lyakh, Arkadiy

Degree

Doctor of Philosophy (Ph.D.)

College

College of Engineering and Computer Science

Department

Electrical and Computer Engineering

Degree Program

Electrical Engineering

Format

application/pdf

Identifier

CFE0008167; DP0023510

URL

https://purls.library.ucf.edu/go/DP0023510

Language

English

Release Date

August 2021

Length of Campus-only Access

1 year

Access Status

Doctoral Dissertation (Open Access)

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